BULLETIN OF MARINE SCIENCE, 46(2): 274-286,1990

MORPHOMETRY AND SIZE AT MATURITY OF ORNATUS (BRACHYURA, ) IN BERMUDA

Paul A. Haefner, Jr.

ABSTRACT Morphometry and size at maturity are described for 196 specimens of Ca/linectes ornatus collected in Mullet Bay, Bermuda during summers of 1981 and 1987. Carapace width in- cluding and excluding lateral spines, body depth, and male abdomen width exhibited linear and isometric growth relative to short carapace length (CSL), the independent variable. Female abdomen width and chelar propodallength, width, and depth were allometric. Prepubertal (near 20 mm CSL) and pubertal molts (near 30 mm CSL) of males were inferred from changes in allometry of chelar propodal dimensions. The prepubertal molt of females (near 24 mm CSL) was revealed by an allometric change in abdominal width and cheliped dimensions. Allometric changes were correlated with morphological changes in the abdomen and pleopods and with gonadal development. Females attain puberty (near 45 mm CSL) at terminal ecdysis as metamorphose to the adult configuration. The species is heterochelic and hetero- dontic. The molariform claw occurred on the right side of 83.5% of all crabs (no significant difference between sexes). Cheliped laterality changes with age; frequency of "right-hand- edness" decreases with increasing size (age). Highly significant differences occurred between molariform (right) and serratiform (left) chelipeds for all dimensions for both sexes.

Few papers have been published on the biology of the Brachyura of Bermuda since Verrill's (1908) monograph. Markham and McDermott (1980) listed 106 Bermudan brachyurans, and Chace et al. (1986) provided diagnostic and distri- butional comments for 55 of those species, but the natural history and reproductive biology of many of those species have not been described. Callinectes ornatus is a relatively large portunid closely related to the commercial blue crab, C. sapidus, of the Atlantic and Gulf coasts of North America (Williams, 1974). Although C. ornatus might be of potential commercial value in Bermuda, its significance is more likely dependent upon its ecological role as scavenger, predator, and food resource for other aquatic organisms and shore birds. C. ornatus ranges from North Carolina to Brazil, including the Caribbean is- lands, and Bermuda (Verrill, 1908). Although records indicate tolerance to a broad salinity range, most collections have been made in warm (18-3 1°C), high salinity (18-350/00)water (Williams, 1974; Norse, 1978). Spawning probably occurs year- round, based on evidence from museum specimens of ovigerous females collected in nearly every month (Williams, 1974). Seasonal abundances of C. ornatus on seagrass beds in the Indian River lagoon in Florida (Gore, 1977) and of C. arcuatus and C. toxotes on the Mexican Pacific coast (Paul, 1982) appear to be related to seasonal changes in rainfall; in each instance, maximum abundance occurred during the dry season. Paul (1982) observed distinct spawning seasons and some segregation of the sexes within the estuarine lagoon system for both species. This paper describes the morphometry and size at maturity of C. ornatus in Mullet Bay, Bermuda.

METHODS

All specimens were collected in Mullet Bay, a Thalassia embayment opening into Ferry Reach in St. Georges' Parish, Bermuda. A long-handled, "D-shaped" dipnet was used to collect crabs in the

274 HAEFNER: MORPHOMETRY OF CALLINECTES ORNATUS 275 lower intertidal zone within one hour of low tide. Collections in 1981 were made during the first three weeks of August; in 1987, they were made from 17 June to 17 July. All specimens were returned to the laboratory and either refrigerated or maintained in running seawater prior to examination. The following measurements were made on each specimen: carapace width including (CLW) and excluding lateral spines (CSW); carapace length excluding frontal spine (CSL); body depth (BD); abdomen width of the fourth and sixth segments (FAW4, FAW6) in females, and the fused third-fifth segment of males (MAW); propodal dimensions of the right and left chelipeds: length (RCPL, LCPL),. width (RCPW, LCPW), and depth (RCPD, LCPD). Fresh, entire, intact crabs were blotted dry and weighed (WT) to the nearest 0.1 g. The abdomens and pleopods were examined to assess maturity. I recognized four progressive stages of development of the male abdomen. In the immature stage, the abdomen is sealed in a flexed position to the sternum, and the pleopods collectively are enclosed within a transparent tissue sheath. A prepubertal abdomen is sealed, but the pleopods are unsheathed. In the pubertal stage, the abdomen is unsealed but partially locked to the sternum by paired tubercles, similar to the device of C. sapidus (Pyle and Cronin, 1950). The penis is inserted in the gonopods. An adult male has a free, fully extensible abdomen. A female abdomen is considered immature if it is sealed and the vulvae are indistinct. In the prepubertal stage, the vulvae are evident, but the abdomen is sealed to the sternum. The penultimate instar female possesses a triangular, lightly pigmented abdomen. The adult female has the characteristic broadened, heavily pigmented and fully extensible abdomen, and setose pleopods. Squash preparations of vasa deferentia were observed microscopically for existence of spermato- ph ores, a sign of sexual maturity (Haley, 1973). Squash preparations of ovaries were examined mi- croscopically to determine stages of development (Pradeille-Rouquette, 1976; 1978). Samples of fluid were withdrawn from incisions in the female spermathecae and examined microscopically for presence of sperm or spermatophores. Plots of each measurement relative to CSL, the selected reference variable, were examined for linearity. Curvilinear relationships were subjected to bivariate analysis in which bivariate ratios (Y/CSL) were determined for each of the suspect variables. Discontinuities in the series reveal changes in the rate of growth ofa given dimension and often are indicative of size ranges within which crabs undergo pubertal and maturational molts (Gore and Scotto, 1983; Davidson and Marsden, 1987). Crabs were grouped into 5 mm (CSL) size classes, and cross tabulations (contingency tables) of developmental stages of abdomen, pleopods, and gonad were tested by Chi-square analysis. These data arrays were compared with the bivariate discontinuities to assess the reliability of the bivariate analyses in predicting stages of sexual maturity. Linear least squares regression equations were derived for each parameter for the total sample of crabs as well as for data subsets which were selected on the basis of gonadal and bivariate analyses. Allometry of growth was examined by applying the equation CSL = aXb to logarithmically transformed data, where (a) is the intercept, and b is the allometric constant. Randomness ofheterodentition and heterochelation with respect to handedness was tested by Chi- square analysis. The dimensions of the major (molariform) chelae were compared with those of the minor (serratiform) chelae by matched pair analysis.

RESULTS The relationships between CSL and the dimensions CLWand CSW are linear and isometric (Table 1).The BD:CSL relationship is linear with positive allometry. Sexual dimorphism is not evident in these dimensions. Covariance analysis of restricted data sets (inclusion of males and females within the same CSL range) revealed heterogeneity of variance for two of the regressions tested (Table 2). Although this normally precludes use of the pooled equation to describe the total population for the dimension in question (Snedecor and Cochran, 1967), the marginally significant test of variance, coupled with non-significance of the tests for regression and intercept, support use of the pooled equations for CLW, CSW and BD. The log-log equation for the weight-length relationship (Table 1)is an acceptable model and, for reasons stated above, the pooled equation is valid even though heterogeneity of variance was revealed by covariance analysis (Table 2). The male abdomen width:CSL relationship is linear and isometric (Table 1). The female abdomen width:CSL relationships differ from each other (Table 1). 276 BULLETIN OF MARINE SCIENCE, VOL. 46, NO.2, 1990

Table I. Regression analyses of body dimensions of Ca/linecles ornatus. based on short carapace length (CSL) as independent variable. Adult female excluded from analyses. Constant of allometry (b), based on log-log transformations, provided for all relationships. Asterisks indicate positive allom- etry

Y variable Sex N Least square regression r' x 100 b CLW M 116 y= 1.078 + 2.096X 99.58 0.988 CLW F 75 Y = -0.209 + 2.159X 99.35 1.013 CLW M+F 190 y= 0.880 + 2.109X 99.50 0.993 CSW M 114 Y = -0.926 + 1.742X 99.62 1.034 CSW F 74 Y = -0.819 + 1.734X 99.72 1.026 CSW M+F 186 Y = -0.912 + 1.740X 99.65 1.031 BD M liS Y = -0.511 + 0.590X 99.73 1.048* BD F 76 Y = -0.453 + 0.586X 99.65 1.060* BD M +F 189 Y = -0.516 + 0.590X 99.73 1.051 * WT M 105 LOG Y = -3.415 + 3.163 LOG X 99.83 WT F 57 LOG Y = -3.379 + 3.133 LOG X 99.79 WT M +F 160 LOG Y = -3.411 + 3.159 LOG X 99.81 MAW M 118 y= 0.694 + 0.496X 99.47 0.960 FAW4 F 73 Y = -0.868 + 0.607X 98.27 1.079* FAW6 F<24mmCSL 51 Y= -1.416 + 0.319X 96.32 1.409* FAW6 24-38 mm CSL 22 Y = -3.676 + 0.414X 84.44 1.455*

Although both are allometric, the relationship of FA W4:CSL is linear (Fig. 1) whereas FAW6:CSL is curvilinear (Fig. 2). Bivariate ratio analysis of the FAW6: CSL relationship revealed a discontinuity in the series, spanning the 21-27 mm CSL size range. For that reason the data were divided into two arrays with 24 mm CSL selected as the size of transition (Table 1). The level of allometry of FA W6 is highly positive and increases from the smaller to the larger size class (Fig. 2). Callinectes ornatus is heterodontic. Teeth of the minor claw are more angular and serrate than those of the major claw. The molariform (major) claw occurred on the right side of 83.5% of the 164 crabs examined (Table 3). There was no significant difference between sexes for this trait x2 = 0.638, P > 0.25). There is evidence that cheliped laterality changes with age (Table 3). All young individuals « 10 mm CSL) had the molariform chela on the right side. The frequency of "right-handedness" decreased with increasing size. This species is also strongly heterochelic, with highly significant differences between right and left chelipeds for all three chelar dimensions for both sexes (Table 4). The right (major) cheliped is markedly larger than the left (minor) cheliped. Bivariate analyses of cheliped dimensions of both the molariform and serra- tiform claw revealed two discontinuities in the male series (Table 5, Figs. 3-5)

Table 2. Covariance analyses of restricted data sets for male and female Callinectes ornatus. based on CSL as independent variable. Significance of F ratios determined at 0.05 (*) level

Dependent variable F var df Freg df F intercept df

CLW 1.57 92, 72 0.224 1,164 3.274 1, 165 CSW 1.727* 89, 70 0.518 1,160 3.141 I, 160 BD 1.620 90, 72 0.771 1,162 3.050 I, 163 WT 1.934* 104, 56 0.390 1,160 1.890 1,160 HAEFNER: MORPHOMETRY OF CALLfNECTES ORNATUS 277

25 E .s ..•. 20 I- Z w ::i1 Cl 15 w en FEMALE ~ I- 0 10 § z w ::i1 5 0 0 CD c:r: I 0 , I I I I I 0 5 10 15 20 25 30 35 40 SHORT CARAPACE LENGTH (mm)

E.s 12 II) I- Z w 9 ::i1 Cl w en 6 FEMALE

z 3 w ::i1 o o I CD o c:r: I I I I I I o 5 10 15 20 25 30 35 40 SHORT CARAPACE LENGTH (mm) Figure 1 (upper). Female Callinectes ornatus. Growth of fourth abdominal segment (FAW4) relative to carapace length (CSL), N = 73. Dots represent single values; circles, two measurements; triangles, three or more. Figure 2 (lower). Female Callinectes ornatus. Growth of sixth abdominal segment (FAW6) relative to carapace length (CSL), N = 73. See Figure 1 for definition of symbols. Two values obscured in the plot. and one in the female series (Table 6, Figs. 6-8). All subset cheliped:CSL rela- tionships, with the exception of the propodal width and depth for the smallest male size class, are positively allometric (Table 5). Generally, the level of positive allometry increases from the smaller to the larger size classes for all cheliped dimensions as the slope of the equation increases and the intercept is depressed. For males, the level of allometry of propodal depth decreases in the third size class but never approaches the lower value of the constant of the smallest size class (Fig. 5). Relationships for the minor chela are similar to those of the major 278 BULLETIN OF MARINE SCIENCE, VOL. 46, NO.2, 1990

Table 3. Cheliped laterality of Callinectes ornatus, expressed as percentage of molariform (major) chelae by 5 mm CSL size classes

Males Females Total CSL N right left N right left N right left

5-9 12 100 0 3 100 0 15 100 0 10-14 17 100 0 14 85.7 14.3 31 93.5 6.5 15-19 9 77.8 21.2 16 87.5 12.5 25 84.0 16.0 20-24 16 87.5 12.5 16 93.8 6.2 32 90.6 9.4 25-29 7 57.1 42.9 7 85.7 14.3 14 71.4 28.6 30-34 16 87.5 12.5 7 71.4 18.6 23 82.6 17.4 35-39 11 63.6 36.4 2 100 0 13 69.2 30.8 40-44 8 50.0 50.0 0 8 50.0 50.0 45-49 2 50.0 50.0 1 0 100 3 33.3 66.7 Total 98 81.6 18.4 66 86.3 13.7 164 83.5 16.5

chela, with the exception that propodal depth of male crabs < 19 mm CSL is positively allometric (Table 5). The most conspicuous difference between males and females occurs in the propodal length dimension (Tables 5 and 6, Figs. 3 and 6). Whereas the CPL allometry is similar in the smallest « 19 mm CSL) size class, the allometric constant is much greater in males than in females among larger crabs (> 19 mm CSL). Male crabs attain sexual maturity at a size as small as 30-34 mm CSL (Fig. 9). More than 88% of crabs> 35 mm CSL possessed vasa deferentia with spermato- phores; all crabs >44 mm were mature. All crabs <30 mm CSL either lacked developed gonads or had vasa deferentia lacking spermatophores. Immature go- nads were observed in crabs as small as 10-14 mm CSL and as large as 30-34 mm CSL. The correlation between the morphological changes of the male abdomen and pleopods and gonadal development is high (Table 7). Over 95% of males with mature gonads were larger than 35 mm CSL and had fully functional adult ab- domens and gonopods, whereas 85% of the specimens with undeveloped gonads had sealed (immature) abdomens. However, it is likely that what externally ap- pears to be a fully functional male may not be physiologically mature. Only 70% of males judged to be adults on the basis of external morphology contained spermatophores in the vasa deferentia. Only one adult female crab was collected. The specimen measured 45.2 mm CSL, possessed a previtellogenic gonad, and had spermatophores in enlarged seminal receptacles. That crab is the sole representative of the 45-49 mm CSL

Table 4. Matched pair analysis of chelar propodal dimensions for Callinectes ornatus. All compar- isons of right (molariform) claw with left (serratiform) claw significant at 0.0 I level (Asterisks indicate positive allometry)

Dimension Sex N

RCPL-LCPL M 77 12.28** F 54 10.89** RCPW-LCPW M 76 7.32** F 54 11.50** RCPD-LCPD M 77 12.46** F 54 11.45** HAEFNER: MORPHOMETRY OF CALLINECTES ORNATUS 279

70

E .s 60 Cl ....I W J: 50 (.) II: ...0 Cl 40 :;; MALE :s: t- el z 30 W ....I ....I Cl a 20 0 ll. 0 II: o •• ll. 10 ... ~~...

0 0 5 10 15 20 25 30 35 40 45 50 SHORT CARAPACE LENGTH (mm)

14

"E12 S- et ~ 10 ::I: U II: Q 8 et ::;; MALE . :i b 6 . ~ . . ...I ... . t5 4 /.. o . a. o o o • II: ... a. 2 o· • ~. . .

o o 5 10 15 20 25 30 35 40 45 SHORT CARAPACE LENGTH (mm) Figure 3 (upper). Male Callinectes ornatus. Relationship of molariform chelar propodallength (CPL) to carapace length (CSL), N =: 79. See Figure I for definition of symbols. Seven values obscured in the plot. Figure 4 (lower). Male Callinectes ornatus. Relationship of molariform chelar propodal width (CPW) to carapace length (CSL), N = 79. See Figure I for definition of symbols. Three values obscured. 280 BULLETIN OF MARINE SCIENCE, VOL. 46, NO.2, 1990

21

E'18 ! < ill 15 ::t (,) II: ~ 12 :;;< MALE :£ .. ~ 9 w Q ....I .. . .. ~ 6 o a. / o II: a. 3 .'O~ ~ o o 5 10 15 20 25 30 35 40 45 SHORT CARAPACE lENGTH (mm)

E' 50 ! ....I< W ::t 40 (,) II: 0 <.. 30 :;; FEMALE :£ ~ 20 Clz w ....I ....I .0 < 10 Q 0 .. a. ~ 0 II: a. 0 o 5 10 15 20 25 30 35 40 45 SHORT CARAPACE lENGTH (mm) Figure 5 (upper). Male Callinectes omatus. Relationship of molariform chelar propodal depth (CPD) to carapace length (CSL), N = 70. See Figure I for definition of symbols. One value obscured. Figure 6 (lower). Female Callinectes omatus. Relationship of molariform chelar propodal length (CPL) to carapace length (CSL), N = 57. See Figure I for definition of symbols. Four values obscured. size class in Figure 10. The previtellogenic stage of ovarian development was observed in crabs as small as 20-24 mm CSL, but crabs as large as 30-34 mm CSL failed to exhibit any gonadal development. The correlation of secondary sexual characters of the abdomen with female gonadal development is high (Table 8). None of the crabs with immature abdo- mens had detectable gonads, whereas 87.5% of the penultimate instar crabs (and the adult) contained previtellogenic ovaries. Of crabs with either immature or pre-pubertal abdomens, only 15% had gonads, and those were previtellogenic. HAEFNER: MORPHOMETRY OF CALLINECTES ORNATUS 281

12 e E ~10 ....I '"W J: (.) B lr 0.., ~'" FEMALE :r. 6 el- 3E 4 . ....I '"e 0 o • D. 0 2 ... lr . . D. / 0 0 5 10 15 20 25 30 35 40 45 SHORT CARAPACE LENGTH (mm)

e15 !.

iil12'" J: u lr ~ 9 ~'" FEMALE :r. li: 6 w ... e . .. ,. ....I o ~ 3 . . . o • • 0 oD. / lr D. 0 o 5 10 15 20 25 30 35 40 SHORT CARAPACE LENGTH (mm) Figure 7 (upper). Female Ca/linectes ornatus. Relationship of molariform chelar propodal width (CPW) to carapace length (CSL), N = 57. See Figure 1 for definition of symbols. Three values obscured. Figure 8 (lower). Female Callinectes ornatus. Relationship of molariform chelar propodal depth (CPD) to carapace length (CSL), N = 57. See Figure I for definition of symbols. One value obscured.

DISCUSSION The growth format of C. ornatus females is determinate, and that of males is indeterminate as is the case in C. sapidus (Van Engel, 1958). Maturity in the female is delayed until the instar following terminal ecdysis (Hard, 1942; Cronin, 1942). This study also revealed that C. ornatus females, which molt to a final sexually mature instar, fit the allometry of size pattern rather than allometry of growth which is characteristic for males (Hartnoll, 1982). Morphometric analysis revealed transitions in the abdominal width and che- liped data series of C. ornatus. It is often inferred that such transitions are related 282 BULLETIN OF MARINE SCIENCE, VOL. 46, NO.2, 1990

Table 5. Regression analyses of cheliped dimensions of male Ca//inectes ornatus, based on short carapace length (CSL) as independent variable. Constant of allometry (b), based on log-log transfor- mations, provided for all relationships (Asterisks indicate positive allometry)

Y variable CSL(mm) N Least square regression r' x 100 b Major claw CPL <19 31 y = -0.781 + 0.989X 96.89 1.073* CPL 19-29 23 Y = -6.783 + 1.334X 91.05 1.323* CPL 30-48 25 Y = -15,108 + 1.558X 95.98 1.329* CPW <19 31 Y= 0.038 + 0.201X 94.64 0.963 CPW 19-29 22 Y = -1.189 + 0.291X 91.35 1.221 * CPW 30-48 26 Y = -2.656 + 0.344X 90.84 1.233* CPO <19 31 Y = -0.018 + 0.278X 92.13 0.997 CPO 19-29 22 Y = -2.472 + 0.478X 89.44 1.322* CPO 30-48 26 Y = -2.520 + 0.455X 90.97 1.179* Minor Claw CPL <19 30 Y = -0.883 + 0.960X 97.12 1.080* CPL 19-29 25 Y = -4.847 + 1.193X 93.56 1.198* CPL 30-48 30 Y = -15.130 + 1.521X 91.55 1.313* CPW <19 31 Y= 0.059 + 0.178X 93.98 0.969 CPW 19-29 25 Y = -1.508 + 0.266X 85.68 1.300* CPW 30-48 30 Y = -2.828 + 0.311X 83.82 1.251 * CPO <19 31 Y = -0.212 + 0.261X 91.48 1.075* CPO 19-29 25 Y = -2.419 + 0.379X 85.55 1.378* CPO 30-48 30 Y = -2.704 + 0.393X 86.59 1.200* to pre-pubertal and pubertal changes associated with gonadal development and the onset of sexual maturity (Hartnoll, 1982; Gore and Scotto, 1983). This study presents evidence that supports such inferences. In male crabs, allometric transitions that occur in the cheliped dimension series for the 15-19 mm and 30-34 mm CSL size ranges are highly correlated with gonadal development and changes in abdomen and gonopod morphology. These

Table 6. Regression analyses of cheliped dimensions of female Ca//inectes ornatus, based on short carapace length (CSL) as independent variable. Adult female excluded from analyses. Constant of allometry (b), based on log-log transformations, provided for all relationships. Asterisks indicate positive allometry

Y variable CSL(mm) N Least square regression r' x 100 b Major Claw CPL <19 23 Y = -1.437 + 1.041X 95.99 1.101* CPL 19-38 34 Y = - 3.307 + 1.179X 98.80 1.128* CPW <19 23 Y = -0.411 + 0.236X 92.50 1.077* CPW 19-38 34 Y = -1.571 + 0.306X 96.18 1.279* CPO <19 23 Y = -0.719 + 0.338X 91.95 1.077* CPO 19-38 34 Y = -2.399 + 0.406X 96.48 1.299* Minor Claw CPL <19 21 Y = -0.955 + 0.944X 89.88 1.053* CPL 19-38 36 Y = -4.971 + 1.189X 98.24 1.173* CPW <19 21 Y = -0.009 + 0.181X 85.22 0.942* CPW 19-38 36 Y = -1.055 + 0.249X 99.06 1.204* CPO <19 21 Y = -0.371 + 0.271X 88.19 1.082* CPD 19-38 36 Y = -1.629 + 0.354X 97.93 1.199* HAEFNER: MORPHOMETRY OF CALL/NECTES ORNATUS 283

o UNDEVELOPED cJ o SPERMATOPHORES ABSENT 5 •• SPERMATOPHORESPRESENT 3 100 - ,.g 9 18 12 80 - 9 W <.9« I- 60 - 16 9 Z W 0 a: 40 - W a...

20 -

0 l ,11 I 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 CSL(mm) Figure 9. Gonadal development of male Callinectes ornatus relative to carapace length (CSL). Num- bers above bar clusters indicate sample size for each size group. transitions reflect the physiological changes that accompany reproductive devel- opment at the pre-pubertal and maturation molts. For female crabs, the single allometric change in the abdomen width series occurs near 24 mm CSL while that in the cheliped dimension series occurs near 19 mm CSL. Transitions in growth of the chelipeds occur earlier in ontogeny than changes in the abdomen. Claw dimensions change in response to the insurgence of the gonad precursor. This is followed by changes in abdominal development which parallel ovarian development and growth during the previtellogenic stage. It is known that abdominal changes occur prior to vitellogenesis. The ovary in the adult was not mature. Newcombe et al. (1949) identified two changes in allometry of the length-width relationship of C. sapidus, attributing one to the change between early and later immature crab stages and the other to onset of sexual maturity. This corresponds to the terminal molt in the female. It is only at this time that the crab copulates and ovarian development begins (Hard, 1942; Cronin, 1942).

Table 7. Contingency table of abdomen morphology and gonad development for male Callinectes ornatus

Gonad

Abdomen Undeveloped Immature Mature Total Immature 23 7 0 30 Pre-puberty 0 4 0 4 Puberty I 17 I 19 Adult 3 7 23 33 Total 27 35 24 86

Chi' = 83.7, P = O. 284 BULLETIN OF MARINE SCIENCE, VOL. 46, NO.2, 1990

(') 0 UNDEVELOPED +' III PREVITELLINE 9 13 2 100 - - - - 7 .~ - Iro~ 80 - II: w ~t~W Ii CJ ~'t: 11 18 &1 w1t1 ~ 60 - r-- Z 6 W r--~ ::;:=.: •.• " () , ~::: •. ..;« ,:;:::::.;:(:, a: 40 I W - a.. I II I I I itt ':~:;:m: 20 - ~t:H ~~':.;.:-:. :~~:t::% It, I '.:.;.:.;-;.;. il If :tll o III I 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 CSL(mm) Figure 10. Gonadal development of female Callinectes ornatus relative to carapace length (CSL). Numbers above bar clusters indicate sample size for each size group.

Both C. ornatus and C. sapidus possess dimorphic chelipeds in both sexes. Hamilton et al. (1976) demonstrated that the pattern of cheliped laterality in C. sapidus is related to age. All blue crabs begin life with right molariform and left serratiform claws, but the incidence of right-handedness decreases with increasing size of the individual. The pattern in C. ornatus is similar to that of C. sapidus, although the percentage oflarge crabs possessing the crusher cheliped on the right is much lower (50%) in the former than in the latter species (74%). This trend, which is most likely a result of regenerative replacement of the crusher with a serratiform claw (Hamilton et aI., 1976), is not unique to species of Callinectes. Simonson (1985) observed that 88% of juvenile stone crabs (Menippe mercenaria; Xanthidae) reared from eggs reversed handedness within the first regenerative molt when their crushers were experimentally removed. She attributed the reversal of handedness by young juveniles as the most likely cause of the observed decrease

Table 8. Contingency table of abdomen morphology and gonad development for female Cal/inectes ornatus

Gonad Abdomen Undeveloped Previtelline Total Immature 15 0 15 Pre-puberty 26 7 33 Penultimate I 6 7 Adult 0 I I Total 42 14 56 Chi' - 22.01, P = 0.0001. HAEFNER: MORPHOMETRY OF CALL/NECTES ORNATUS 285 in right-handedness to 80% among older juveniles and small adults in natural stone crab populations. The variation in incidence of handedness among larger crabs in natural pop- ulations is most likely dependent on the ability of individuals to survive without a crusher. While some species exhibit a decreased incidence of reversal with age because of prolonged regenerative replacement time in older crabs (Simonson, 1985), other species (Uca spp.) do not reverse handedness (Barnwell, 1982). The observed allometric patterns for the male chela are comparable to those reported for other Brachyura (Hartnoll, 1974, 1982). Male chelae normally have a high positive allometry asjuveniles and a large increase in relative size at puberty. In females, however, the chelae of C. ornatus grow with a positive allometry that is equal to or exceeds that of males during the juvenile phase. Moreover, the female chelae also increase in relative size at the pubertal molt, although the increase is less than that of males. This is clearly different from the pattern reported for certain Brachyura (Hartnoll, 1982), but some portunids lack separate growth phases (DuPreez and McLachlan, 1984; Davidson and Marsden, 1987). The growth of the male abdomen of most Brachyura is expected to be isometric throughout the life span (Hartnoll, 1982). Such is the case for C. ornatus. However, a marked positive allometry is characteristic for the abdomen offemale Brachyura, and that allometry should increase significantly at the pubertal molt (Hartnoll, 1982). Females of the genus Callinectes, however, deviate from that pattern be- cause the abdomen characteristically retains the triangular shape associated with the juvenile stage until terminal ecdysis. At that time, the abdomen undergoes a metamorphosis in shape and color (Hard, 1942; Van Engel, 1958). My data for C. ornatus bracket the juvenile phase of growth and reveal a slight change in allometry in the sixth abdominal segment, even in the triangular shape. This may be the first observation of such a transition among the Callinectes species. Ab- dominal growth of other species of portunids (DuPreez and McLachlan, 1984; Haefner, 1985; Davidson and Marsden, 1987) is similar to that of the brachyura in general, in that the abdomen gradually changes size and shape over a series of pubertal molts.

ACKNOWLEDGMENTS

This research was supported by an RIT College of Science Summer Research Fellowship Grant, and by a Grant-in-Aid from the Bermuda Biological Station for Research, Inc. Contribution No 1194 from the Bermuda Biological Station for Research, Inc.

LITERATURE CITED

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DATEACCEPTED: November 3, 1988.

ADDRESS: Department oj Biology, Rochester Institute oJ Technology, P.O. Box 9887, Rochester, New York /4623.